Idea: Jasonette Builder

I've been thinking abi about json builder for jasonette.

The idea is basically using [blockly ](https://developers.google.com/blockly/) custom blocks to generate the json.

Just throwing this out here in case anyone has a better idea or maybe working on it or something similar and maybe get some feedback before i start (in like 2 weeks)

No files, tests, or entry points are named. Start by reviewing the Jasonette Android project and Blockly's custom-block documentation; define the builder's scope and an acceptance criterion before implementation.

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